“Is the glass half empty or half full?” when you look at a glass of water do you look at it as being half empty or half full? Most people will look at it and say that its half empty. But you got others who will argue and say its half full. This expression is an outlook on life. You could look at a situation your dealing with and say that there is no way out, that your done, or you cant handle it and that you give up. Or you could look at a situation and say that you can fix what's going on. Its about being negative or positive toward something. If someone gives you a challenge but you say “I cant do that” than your being negative but if you say “I can achieve that goal.” than your being positive.

Another famous quote would be “When life gives you lemons make lemonade.” This quotes telling you to not always be mad at something because you didn't get exactly what you wanted. But its saying to do with what you got. When your mom or someone gives you fifty dollars to go shopping for new shoes and your wanting the ones with the sparkles on the side and their sixty dollars you might have to emphasize and buy the cheaper one. These are two famous quotes that are the same in a way they both try to teach you the meaning of life but with a little thought.
So the next time life throws you a situation that you don't know how to achieve look at the positive side of it first before you react in a negative way.